1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.support.v4.view; 18 19 /** 20 * Helper for accessing features in <code>ScaleGestureDetector</code> introduced 21 * after API level 19 (KitKat) in a backwards compatible fashion. 22 */ 23 public class ScaleGestureDetectorCompat { 24 static final ScaleGestureDetectorImpl IMPL; 25 26 interface ScaleGestureDetectorImpl { 27 setQuickScaleEnabled(Object o, boolean enabled)28 public void setQuickScaleEnabled(Object o, boolean enabled); 29 isQuickScaleEnabled(Object o)30 public boolean isQuickScaleEnabled(Object o); 31 } 32 33 private static class BaseScaleGestureDetectorImpl implements ScaleGestureDetectorImpl { 34 @Override setQuickScaleEnabled(Object o, boolean enabled)35 public void setQuickScaleEnabled(Object o, boolean enabled) { 36 // Intentionally blank 37 } 38 39 @Override isQuickScaleEnabled(Object o)40 public boolean isQuickScaleEnabled(Object o) { 41 return false; 42 } 43 } 44 45 private static class ScaleGestureDetectorCompatKitKatImpl implements ScaleGestureDetectorImpl { 46 @Override setQuickScaleEnabled(Object o, boolean enabled)47 public void setQuickScaleEnabled(Object o, boolean enabled) { 48 ScaleGestureDetectorCompatKitKat.setQuickScaleEnabled(o, enabled); 49 } 50 51 @Override isQuickScaleEnabled(Object o)52 public boolean isQuickScaleEnabled(Object o) { 53 return ScaleGestureDetectorCompatKitKat.isQuickScaleEnabled(o); 54 } 55 } 56 57 static { 58 final int version = android.os.Build.VERSION.SDK_INT; 59 if (version >= 19) { // KitKat 60 IMPL = new ScaleGestureDetectorCompatKitKatImpl(); 61 } else { 62 IMPL = new BaseScaleGestureDetectorImpl(); 63 } 64 } 65 ScaleGestureDetectorCompat()66 private ScaleGestureDetectorCompat() {} 67 68 /** 69 * Set whether the associated <code>OnScaleGestureListener</code> should receive onScale 70 * callbacks when the user performs a doubleTap followed by a swipe. Note that this is enabled 71 * by default if the app targets API 19 and newer. 72 * @param enabled true to enable quick scaling, false to disable 73 */ setQuickScaleEnabled(Object scaleGestureDetector, boolean enabled)74 public static void setQuickScaleEnabled(Object scaleGestureDetector, boolean enabled) { 75 IMPL.setQuickScaleEnabled(scaleGestureDetector, enabled); 76 } 77 78 /** 79 * Return whether the quick scale gesture, in which the user performs a double tap followed by a 80 * swipe, should perform scaling. See <code>setQuickScaleEnabled(Object, boolean)<code>. 81 */ isQuickScaleEnabled(Object scaleGestureDetector)82 public static boolean isQuickScaleEnabled(Object scaleGestureDetector) { 83 return IMPL.isQuickScaleEnabled(scaleGestureDetector); // KitKat 84 } 85 } 86